Most commercial properties include a number of building systems that monitor and regulate various functions of the building for the comfort and well-being of the tenants. These building systems include security systems, fire control systems, and elevator systems. One prevalent and important building system is the environmental control system.
An environmental control system is used to regulate the temperature and flow of air throughout a building. A heating, ventilating, and air conditioning (HVAC) system maintains environmental conditions within a building for the comfort of the occupants. A typical HVAC system is divided into zones and is adapted to maintain each zone within predefined environmental parameters such as humidity and temperature. The air conditioning for a building typically includes one or more chillers for cooling air and one or more heaters for warming air. An air handling unit (AHU) supplies conditioned air to ductwork that distributes the air to each of the zones. The AHU generally includes elements for introducing outdoor air into the system and for exhausting air from the system. An AHU is typically comprised of a centrifugal blower that pressurizes the conditioned air for distribution though a duct at a desired flow rate. Variable air volume (VAV) boxes are control boxes coupled to ducts to further regulate the air flowing through a zone. Air flow regulation is achieved by controlling a damper position within the box. The dampers are maneuvered through a range of movement from being 100% open to 0% open, i.e., closed, by one or more actuators. The control components of a VAV box typically store one or more set points. If multiple set points are stored, one set point may be used for when the building system is in a heating mode, while another may be used when the system is in a cooling mode. The VAV box regulates temperature within a room by opening and closing the damper to adjust the volume of conditioned air delivered to a room so the room temperature is driven towards the set point. The speed of a motor that drives the blower is controlled to regulate fan speed and, correspondingly, air flow in the system. An important component of a building environmental system is the control system that varies the fan motor speed and the position of the various dampers to maintain pressure and flow rate set points for the system.
Control systems for building systems are increasingly reliant upon computer and network technology. Micro-controllers and the like may be used to operate and maintain actuators for damper position as well as controlling fan speed. These local controllers provide operational data to an overall system controller. The overall system controller is typically a computer that analyzes data received from local controllers to determine whether system parameters, such as set points, are being maintained. If the system parameters are not being met, the system controller issues command messages to one or more building controllers to adjust local control so the system parameters may be achieved. In some previously known systems, the system controller communicates with the building controllers over a computer network. Most typically, the hardware platform for the network is an Ethernet platform and the network software supporting communication over the network is a TCP/IP layer. This structure supports communication between a control application program executing on the system controller and an application program executing on the building controller.
Most building control systems may be described as having three network levels. These levels are the management level network, the building level network, and the floor level network. The management level network may be an Ethernet network that is based on a TCP/IP protocol. This network level typically includes a report server, a building automation server, and at least one building automation client. The building automation server operates as the overall system controller as described above. This server includes a user interface to provide system information that may be understood and evaluated by a human. The management network level may also be coupled to other external networks through supervisory computers, Internet gateways, other network gateways, or network managers. These other networks may have hierarchical levels that may be able to communicate with the management network level.
The management network level in most building systems is coupled to a building level network that is comprised of at least one peer-to-peer modular building controller. The modular equipment controller is a modular, programmable primary controller with a supervisory interface capability to monitor a secondary controller network. The modular building controller monitors and regulates general HVAC applications including air-handling units, chiller/boiler/central plant control and distribution systems, data acquisition, and other multi-equipment applications. The modular building controller provides on-board control of I/O points and central monitoring for distributed secondary control units and other building systems, such as fire, security, and lighting systems. Comprehensive alarm management, historical trend collection, and operator control and monitoring functions are integral to the modular building controller. Typically, a modular building controller may have up to 96 floor level devices coupled to it.
The peer-to-peer building level network coupling the building modular controllers may be an Ethernet network, as is typical of the management level network. Thus, computers on the management level network may communicate with the controllers on the building level network. This enables further integration and evaluation of the monitoring and regulation performed by the building controllers.
Devices coupled together by the floor level network may include terminal equipment controllers, environmental condition sensors, differential pressure monitors, fume hood control monitors, lab room controllers, digital energy monitors, variable frequency drives, variable air volume (VAV) boxes, and other devices. Typically, the floor level network employs a protocol, such as the LonTalk protocol, to support communication between these types of devices and the modular building controllers of the building level network.
The topology of a building environmental system may be rather intricate and involve one or more AHUs, one or more VAV boxes, and a number of sensors for monitoring the effectiveness of the system in maintaining its programmed set points. When a building environmental system is installed in a building, it must be commissioned. Commissioning includes testing the building controllers to determine whether the AHUs and VAV boxes may be controlled to maintain the set point conditions for which the system was designed. This activity requires operating the system at certain predefined conditions and measuring the resulting environmental parameters, such as temperature or pressure. Additionally, some VAV boxes may include heating elements for supplemental heating of air passing through the box. Thus, the operation of the VAV boxes in both heating and non-heating modes needs to be verified. Consequently, commissioning requires the methodical setting of operational conditions, monitoring the operational modes of components within the control system, measuring the environmental results, and evaluating the effectiveness of the system components.
In previously known commissioning methodologies, set points were entered into a control component, the component was activated, and the data collected manually. In response to the laborious efforts require for such testing, computerized testing tools have been developed. However, these computerized tools suffer from a number of limitations. For one, VAV boxes were tested by coupling a computer tool to an individual VAV box and varying the control signal to alter the damper position within the box. The coupling of the test tool to the VAV box required the VAV box to be wired differently during testing than what it was for system operation. Additionally, sensors had to be temporarily mounted or held in proximity to the air discharge of a VAV box and coupled to the computer to obtain measurements regarding the characteristics of the air flow. The computer then analyzed the results for the VAV box to which it was connected and indicated whether that box passed or failed the test.
While this method reduces the amount of manual labor required for system commissioning over previously known systems, it still required coupling and decoupling of the computer tool to each VAV box and the sensors mounted at the box. Furthermore, each VAV box was tested independently so the system condition was static except at the VAV box being tested. Such testing fails to provide information regarding the control of floor level network components through the building level network. Furthermore, after testing, the wiring coupling the test tool had be removed so manual labor was involved in returning the VAV box to its operational setup. To properly identify all of the VAV boxes to be tested, the test personnel had to have a system diagram identifying each VAV box in the system and they had to manually track which ones had been tested and which ones remained to be tested. Similar tracking was required to definitively known whether a VAV box had been calibrated before being tested. If a VAV box was not calibrated before being tested, the time spent testing the VAV box was wasted.
In prior testing methodologies, the computer test tool collected data and either printed it out or presented it on a display. If a VAV box failed a test, the testing personnel had to determine what the cause of the failure might be. This procedure requires the testing tool operator to be knowledgeable about VAV boxes and system parameters in order to propose a possible cause for the failure. Therefore, one or more experienced technicians were required to test and troubleshoot VAV boxes. Such a procedure either adds expense for the use of multiple experienced technicians or time so a single technician can test each VAV box in a system.
What is needed is a computerized test tool that enables testing of multiple VAV boxes without requiring breakdown and setup of the test equipment between VAV box testing.
What is needed is a system that enables measurement data to be developed for system dynamics during VAV box testing.
What is needed is a VAV test tool that determines whether a VAV box has been calibrated before conducting a test of the VAV box.
What is needed is a VAV test tool that can identify the VAV boxes to be tested and track which ones have been tested.
What is needed is a VAV test tool that can test more than one VAV box without having to be coupled and decoupled to each box individually.
What is needed is a VAV test tool that can determine the cause of a test failure without requiring experienced technician intervention.